One of the best things you can do for your manuscript is to join a critique group that really cares about your work. A dedicated fellow writer will not only understand the mechanics of a good manuscript, but they may also have suggestions about plot and pacing that might not have occurred to you. The caveat is, of course, not to edit so much that you lose your own voice and vision for your work ... but that's a topic for another day.
It's especially great if you find another writer who understands your vision for your work and wants to help you get the most out of it. They can tell you where they laugh, where they cry, what alternate wording might work better, and best of all, support you when you're feeling down. A built-in circle of friends who understand the madness of being a writer - and sympathize! Not to mention, they're not family, so they're not going to be too careful if there are things they don't like or understand about your work. They'll tell you - unlike Mom, who might be more worried about your feelings. :)